This invention relates to a packaging material which has good metallic gloss or luster, which is capable of undergoing heat shrinkage, and which is suitable for use as outer jackets or housings for products such as shampoos, rinses, cosmetics, and dry cells.
Shrink packaging by means of a package material in the form of a heat shrinkable plastic film has been widely used in packaging of the barrel part or the entire body of glass and plastic bottles for shampoos, rinses, cosmetics and the like; in packaging of audio products such as video tapes, and cassette tapes; in packaging of dry cells and drinks; and in packaging of confectioneries and boxes of confectioneries. However, when a packaging material comprising a shrinkable plastic film provided with a metal layer, e.g., a metal-deposited layer is used and shrunk, the metal-deposited layer cannot accommodate to the shrinkage of the plastic film. Thus, cracks are generated in the metal-deposited layer, its metallic gloss is lost, and blushing can occur. Accordingly, a metal-deposited layer cannot be used in shrink packaging. In order to develop metallic gloss, a process wherein an ink layer having metallic gloss is used to develop metallic gloss has been used. However, in the case of mere application of metal ink compositions, such ink compositions have intrinsically low metallic gloss and therefore insufficient metallic gloss is obtained.
In packaging of particular products such as video tapes and cassette tapes, a metal-deposited layer has been currently proposed in shrink packaging. In this case, the metal-deposited layer is used at a face region exhibiting little shrinkage so that the metal-deposited layer is not affected by shrinkage.
In such a case, metal cannot be deposited onto the entire packaging material. Further, its exterior appearance and visual impression are poor. Furthermore, it is necessary to carry out complicated steps such as paster and sealant processing. Accordingly, there are many difficulties in the steps for producing a packaging material and in shrinking steps.
Recently, there has appeared a product wherein a packaging material having a shrinkable plastic film provided with a metal-deposited layer is shrunk onto the barrel portion of tubular plastic bottles for shampoos, rinses and the like. In this case, in order to prevent blushing due to wrinkles and cracks of the deposited layer of the name portion of the front, a method wherein only the back and side portions are shrunk and the front is subjected to minimal shrinkage is adopted.
In such a case, in order to limit the portions which are to be shrunk, it is necessary to amply align the packaging material prior to shrinking. Further, the packaging material cannot be easily passed through a heat open tunnel and therefore it is not partially shrunk. Furthermore, it is extremely difficult to control the hot air used in the heat open tunnel.
An object of the present invention is to provide a packaging material which is capable of undergoing heat shrinkage and which has good metallic gloss after heat shrinkage.
This and other objects of the present invention will become apparent from the description presented hereinafter.